The cleaning of motion picture film has presented a long standing problem of great importance to the entertainment industry. The completion of a motion picture results in only one original film which has been handled and spliced many times. The original also represents a very valuable asset which must not be damaged. However, before exhibition numerous copies must be made and the quality of these copies must be as close to the original as possible.
Before a film can be copied it must be cleaned. Otherwise dust, grease and other debris which is on the film will affect light transmission to the copy and thus degrade its quality. Moreover, debris on the original may permanently injure the film surface and degrade its quality also.
Machines for cleaning film are generally available with one group made by Lipsner-Smith Co. of Lincolnwood, Ill. Lipsner-Smith has two models, CF 3000 VCS and CF 3000-MK V. Generally, the Lipsner-Smith machines feature a liquid cleaning system where the film proceeds into a cleaning tank filled with solvent and the solvent is subjected to ultrasonic waves. The film is then sprayed and dried before proceeding to a take-up reel. The Lipsner-Smith machines are advertised to be a closed system so that little solvent vapor can escape and where most of the solvent is reclaimed.
Because the solvent vapors are considered dangerous to both working personnel and the environment, there is a need for venting and a need for the venting to be accomplished in an environmentally safe manner. The solvent handling and reclamation system includes expensive refrigeration, purification, pumping, and filtration equipment, and because the film must also be dried, the drying system includes expensive compressor, heating, and filtering equipment.
Finally, the Lipsner-Smith system uses a sprocket drive for moving the film and this may cause injury to the sprocket openings along the periphery of the film to be cleaned. The Lipsner-Smith machines are relatively complicated and expensive, and they are environmentally dangerous and require the film to be immersed in a liquid. Wetting film is always dangerous because should one part of the film touch another, the two parts will immediately stick to each other and ruin the surface coating. More detail of the Lipsner-Smith machines may be gathered from a patent issued in 1961 to the company, U.S. Pat. No. 2,967,119.
Another company, Peterson International Enterprises Ltd. of Glenview, Illinois makes machines similar to Lipsner-Smith but instead of ultrasonic waves to agitate the solvent, Peterson uses scrubbers in the solvent. All of the problems afflicting the Lipsner-Smith machines also trouble the Peterson machines.
In a recent article in the June, 1993 issue of Image Technology, John P. Pytlak and Dale R. Morrison of the Eastman Kodak Company describe the use of particle transfer rollers ("PTR") for cleaning film. These rollers have an outer layer made of soft polyurethene which produces a roller with a "tacky" surface to which dirt particles will stick if the film comes into contact with the rollers.
While PTR technology offers promise for film cleaning it is in itself insufficient, and thus, there is no safe, economical and efficient system for cleaning film.